What is the first spirit called?

The first spirit is the Ghost of Christmas Past. He takes Scrooge back to some scenes from his earlier years. This part of the book provides us with a useful bit of exposition concerning Scrooge's story, helping us to get a better understanding of him and how he became such an unpleasant old miser.
We learn that Scrooge was desperately unhappy as a boy and was sent away to a boarding school he thoroughly detested. We also learn that Scrooge was very close to Fan, his kind, loving sister who pleaded with her father to allow young Ebenezer to return home and escape his miserable schooldays.
The Ghost of Christmas Past shows us another side of Scrooge, one more human and vulnerable. He even used to like Christmas in the past years, enjoying the seasonal hospitality of his kindly employer, Mr. Fezziwig. However, Scrooge became greedy and ambitious, putting money ahead of all his relationships. He was engaged to be married to Belle, but she broke off the engagement when she realized what kind of a man her fiancé was becoming. The Ghost of Christmas Past presents Scrooge with a scene of Belle, now happily married, enjoying Christmas Eve with her family on the night that Jacob Marley passed away.